Story 1
There is so many plot holes in the story of SAO in things that took away from the story for example in the first arc when the death game took place there was about a 6 episode stretch where Kirito and Asuna did nothing to progress the story they got married and ran around doing random shit that was not needed in the slightest. The whole death game plot wasn't bad on paper but it was very poorly executed. There were times that it was competently forgotten and they went off to do other random stuff that made for extra boring filler episodes.
Art 3
While when the art looked good at some places there are a good bit of repeated scenes where it didn't look so good.
Sound 7
The opening and closing themes for sword art online were very good and I had no problems with the voice actors being annoying.
Characters 4
I'm gonna split this up into a couple different segments
Kirito- Kirito is any 12 year old's dream to be the ultimate bad ass that it isn't even fair to play against.
Asuna- You know i really don't understand Asunas character at all there are times where she was completely different from what she usually is for example in the first couple episodes she is shown as an arrogant shy person but later she is very confident and uses her brain most of the time. But overall I really liked her character design.
The Rest of the Harem- None of these characters even matter and just add extra filler.
Other Characters- Again nobody else matters in the series and are just plot devices that you probably wont care about.
The Good
Asuna had a very good character design that was likable unlike Kirito.
The art looked very good in the boss battles which we didn't see enough of.
The themes for sword art online are very nice sounding and enjoyable.
The marriage arc was sweet and even though it was complete filler I enjoyed it.
Yui was a decent plot device even though she totally contradicted the plots with some of the logic used.
